Image Quality Metrics and Application of the Square Root Integral (SQRI) Metric: An Overview
Final rept. Jan 1989-Jun 1990
DAYTON UNIV OH RESEARCH INST
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The purpose of this report was to present an overview of image quality metrics and evaluate the performance of the Modulation Transformer Function Area MTFA and the Square Root Integral SQRI metrics on displays used at the Air Force Human Resources Laboratory AFHRL. While the MFTA, as indicated by its name, correlates highly with the display modulation transfer function area, the SQRI, developed by Barten 1987, integrates display luminance, contrast as measured through the modulation transfer function, and resolution into a single measure in s different fashion. The scalar results obtained from the metrics act as an image of quality for the display devise. Results of the analyses showed that a image quality metrics lacks the ability to incorproate the relative importance of display luminance b the J measure from the SQRI metric emphasizes low spatial frequency information 5 cycles degrees relative to high spatial frequencies c only on of the two measures developed by Barten, the J index, yielded unambiguous results d small variability in the low spatial frequency of the MF4TF could cause large changes in the resulting SQRI image quality measures and e the concept of the display modulation depth curve or display MTF employed in image quality metrics is ambiguous and requires some form of further standardization. To date, little is known about the manner in which humans combine spatial frequency-based information from displays, and most image quality metrics reflect this lack of knowledge. More basic psychophysical knowledge of these properties is required before image quality metrics will become useful.
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